Low temperature treatment of gases



Jan. 19, 1932. Y M GOBERT I 1,842,263-

4 LOW TEMPERATURE] TREATMENT OF GASES Filed March 13, 1930 Patented Jan. 19, W32

UNITED STATES MAURICE GOiBERT, or ormvrtnn, rnnncn, ASSIGNOR .TO LAIB LIQUIDE, socrnrn ANONYME ro-UR LETUDE nu: LEXPLOITA'IION nus raocnnns GEORGES CLAUDE, or

PARIS, FRANCE Low 'rnnrnnnrunn TREATMENT or cases Application filed March 13, 1930, Serial No. 435,587, and in France march 15, 1929.

The present invention relates to, and has for its object to provide, improvements in the processes of defrosting heat exchangers used in apparatus for the liquefaction or sep- 1 aration of gases by cold, in particular in apparatus for the manufacture of a gas rich in hydrogen by the liquefaction of the other constituents which are mixed therewith in gas treated, and which produce at the endof a certain time, troublesome obstructions. This is the operation called defrosting the exchanger, in which the same proceeding may be adopted as for the heat exchangers of certain apparatus for the manufacture of oxygen and nitrogen by the liquefaction of air, where the solid deposit consists of ice; these apparatus are provided with two exchangers which are put into service alternately. The compressed air is first cooled to the surrounding temperature, or to a temperature slightly higher, in the exchanger to be defrosted, where it circulates in order to heat it, passing thence into the exchanger under normal operation, which aloneis traversed in counter current to the airby the separated and cold gases and in which is produced the usual exchange of heat. A suitable arrangement of cocks and tubes permit placing alternately one or the other of the two exchangers in the position of defrosting or of working.

Now, it has been proven that for apparatus for the liquefactionof coke-furnace and similar gases, such an arrangement may give rise to difiiculties in working from the fact that the coke furnace gas having served for the defrosting is charged with a part of the impurities which it has caused to melt in the exchanger being defrosted, and thatthe said impurities thus carried with the gas into the colder parts of the liquefaction apparatus may give trouble in the working in consequence of the blockages to which they may there give rise. 1 I This defect is remedied, according to the grammatically and by way of example a method of carrying out the present invention, in which a part of the gas rich in methane produced in an apparatus for the partial liquefaction of coke furnace gases is used for the defrosting.

On this drawing Band C are two heat exchangers, one of which is usedfor the cooling of. the incoming coke oven gas while the other is being defrosted. K and K are sets of tubes through which the separated gases are flowing. A is the tube through which the coke oven gas enters and D the tube for the exit of the cooled coke oven gas. E and F are cocks. I, G and H are tubes through which the different separated gases enter the heat exchanger. H, I and G are tubes for the exit of the separated gases which leave the heat exchangers. L, L, M, N, N, X and X- are cocks. P and P are tubes pro vided with cocks for the discharge in the liquid state of the impurities that. were deposited in solid state in the heat exchangers. Z is a heater for a part of the separated gases.

The compressed coke furnace gas enters through A and may pass through the cocks E- and F either into the left-hand heat exchanger B, or into the right-hand heat'ex changer C; it passes out at the top to flow through the tube D to another exchanger working at a lower temperature. I

The separated gases are here supposed to be three in number, that is to say 1st. The gas rich in methane entering through the tube G from the separating ap paratus and the low temperature exchanger just mentioned 2nd. The gas-rich in hydrogen which enters through the tube H;

3rd. The gas rich in carbon monoxide or rich in nitrogen entering through the tube I. These three gases circulate in one or the other of the exchangers B or'C, flowing inside the tubes K or K and passing out at the lower part at H for the second gas, at I for .the third gas, while the first gas passes out,

either a part of it at G and a part at N or N, or wholly at N'or N. The cocks M for the'second as, X and X for the third gas, and finally or L for the first gas, permit the necessary manipulation to be effected. Each of these gases can be used for any purpose whatever, for example, in synthetic or other reactions. In particular the gas rich.

I lows: Suppose that the exchanger B is frosted. In this case, the supply cock E for the coke furnace gas is closed, and the cock F is opened to send the said gas into the exchanger C which it passes through from bottom to top, depositing in the liquid state and then in the solid state its easily condensible impurities such as water and benzol. The cooled gas passes out at the upper part at D.

During this time, the gas rich in hydrogen enters at H into a art of the set of tubes K of the exchanger leaving at H after passing through the cock M, which closes the passage of this same gas through the exchanger B. In the same way, the gas rich in'carbon monoxide or in nitrogen, entering at 1, passes through a part of the tubes K and leaves at I, flowing through the cock X, the cock X being closed. The gas rich'in methane entering at G, passes through the cock L, and is directed into the exchanger G, where it flows through a part of the tubes of the bundle K; a. part of this gas is caused to leave through the cock N, while the balance passes throu h the heater Z where it is heated for example hy a'sup'ply of steam outside the tubes of Z. This portion of gas so heated then passes to the heat exchanger B, where it circulates in the art 'of the, set of tubes K which is traversed ythe gas-rich in methane when this exchanger B is working normally. This hot gas part thus defrosts the exchanger 'B and leaves it through G, after having passed through the cock L the lower cock N is of course closed.

' completed, which is verified. by the'discharge P or P provided at the lower part of the Said exchanger, N is opened to allow When the defrosting of the exchanger'B is the exit there of the whole of the gas rich in in the pressure indicated on the pressure gauge placed after the exchanger in the circuit of the compressed coke furnace gas, the

cocks are manipulated so as to cause the coke V furnace gas to pass into the exchanger B, as

well as the gases separated, and to send a part of the gas rich in methane into the exchangerC to defrost it.

One advantage of this arrangement is to permit the recuperation alternately by the exchangers B and C of the whole of the benzol contained in the coke furnace gas, by changing the exchanger as soon as the quantity of solidified benzol accumulated in the exchanger causea pre-determined loss of pressure, for example, of one atmosphere. It then becomes possible to suppress the heavy oil towers now used to debenzolate coke furnace gas, and even the debenzolation effected in the coking works on the non-compressed gas leaving the furnaces.

One of the advantages of taking onl a part of the separated gas to effect the de rosting consists in that by 'this means the creation of too great a counter pressure on the said gas is avoided, which counter pressure might injure the operation of the separating apparatus proper.

I claim:

1. A process for the low temperature treatment of gases containing low volatile substances that solidify by cooling, which comprises circulating the gases resulting from the low temperature treatment in indirect contact with and counter current to the treated gas alternately in two regions spacially remote one from the other, whereby said easily solidifiable substances deposit along the path of'the treated gas, the gases resulting from the low temperature treatment which have been cir culated in one region being further circulated along those same paths of the other region,

along which they are circulated when the in-. direct contact is effected in said region, so as to melt the substances which previously deposited in solid state along the path of the treated gas. 2.' A rocess for the low temperature treatment 0 gases containing low volatile substances that solidify by cooling, which comprises circulating the gases mesulting from the low temperature treatment in indirect contact with and counter current to the treated gas alternately in two regions spacially remote one from the other, whereby said easily solidifiable substances deposit along the path of the treated gas, a part of the gases resulting from the low temperature treatment which have been circulated in one region being further circulated alongthose same, paths of the other region, along vzhich the corresponding gases are circulated when the indirect contact is -efiected in said region, so as to melt the su'bstances which previously deposited in solid state along the path of the treated gas.

3.- A rocess for the low temperature treatment 0 gases containing low volatile sub stances that solidify bycoolin which comrises circulating the gases re ting from the ow. temperature treatment in indirect contact with and counter current to the treated gas alternately in two regions spacially remote one from the other, whereby said easily solidifiable substances depositalon the path of the treated gas, the gases re ting from the low temperature treatment which have beencirculated in one region being further heated and circulated along those same paths of the other region, along which they are circulated when the indirect contact is efiected in said 26 region, so as to melt the substances which pre- I viously deposited in solid state along the path. of thetreatedgas.

4. A rocessior the low temperature treatment 0 gases containing low volatile sub stances that solidify by coolisllilg, which comprises circulating the gases re ting from the ow temperature treatment in indirect contact v with and counter current to the treated gas alternately in two regions spacially remote one from the other, whereby said easll solidifiable substances deposit along the pa of the treated gas, a part of the gases resulting from the low temperature treatment which have been circulated in one region being further heated and circulated along those same paths otthe other region,'along which the corresponding gases are circulated when the indirect contact is efiected in said region, sons to melt the substances which reviously deposited in solidstate along t e path of the treated gas. In testimony whereof, I aflix m r GOBERT, ICE. 

